In the last decades the significance of the use of antioxidants has increased all over the world in various fields and consequently, the use of the antioxidants has been widespread. Antioxidants ar most often used in the rubber industry and in the plastic industry and in this field the highest requirement is the specific effectivity of the antioxidants and in addition a very important factor is compatibility as well as low tendency to migration etc. The use of antioxidants in agriculture, in the food industry and recently in veterinary science and human therapy has increased significantly. While in the rubber and plastic industry several amine and phenol type antioxidants are used, for the stabilization of fodders, practically only 6-ethoxy-1,2-dihydro-2,2,4-trimethyl-quinoline (EMQ) and 2,6-di-tertiary butyl-hydroxytoluene (BHT) have been used. The antioxidants suitable for the stabilization of fodder mixtures have to meet simultaneously several essential requirements, such as broad spectrum, low toxicity, and freedom from injurious effects. The last point of view is considered in the recommendation of WHO/FAO Nutrition Meeting Ser. No. 40 A, B, C, WHO/FOD AU 67.29, according to which such antioxidants should be used for the mentioned purposes, which have LD.sub.50 values exceeding 5 g/kg body weight. it is known that neither EMQ nor BHT meets this requirement. In spite of this fact these two compounds have been most accepted according to the present state of the art. These two compounds are the best in meeting said complex requirements.
6,6-methylene-bis(2,2,4-trimethyl-1,2-dihydroquinoline) is used in human therapy due to its radiosensitizing properties and it has proven not to be truly suitable for the stabilization of fodders because the extreme sensitivity of its methylene group very often results in coloration in the fatty tissue of the animals.
The antioxidant activity of 6,6'-ethylidene-bis(2,2,4-trimethyl-1,2-dihydroquinoline) called as XAX-M is suitable, its toxicity is low, but upon oxidation the ethylidene group is also oxidized and has a certain coloring effect.
A further disadvantage of XAX-M prepared according to Hungarian patent specification No. 162,358 is that the product is not homogeneous chemically, but according to page 4 of the Hungarian patent specification the polycondensation degree,i.e. the number of dihydroquinoline units changes depending upon the reaction conditions. The products obtained by acetaldehyde or by higher aldehyde condensation form a mixture of condensed molecules containing 2 to 4 dihydroquinoline units. A constant composition cannot be easily ensured, although this is required by the user.
No economic and practical process has been found so far. DOS 35 40 105 relates to the same product and to its property of increasing the coccidiostatic activity of known coccidiostatics.